1. Field of the Invention
This invention relates to material on which a record of letters, figures, etc., is to be made by use of a recording liquid (hereinafter, the materials are referred to simply as recording materials).
2. Description of the Prior Art
Recording by use of a recording liquid or ink has long been made by means of writing tools such as pens, fountain pens, felt pens, etc. Recently, ink-jet recording systems have been developed, where ink is also utilized.
The ink-jet recording system makes a record by forming ink droplets with any of various ink-jetting processes (e.g. electrostatic attractive process, mechanical vibration or displacement process by use, of piezoelectric elements, bubbling process where bubbles are generated by an impulsive heating of ink, etc.), and leading parts or all of the droplets adhere to a recording material such as paper.
For recording in these ways and using liquid ink, ink is generally required not to blot on the recording paper so that the printed letters or figures may not become dim. The ink is also desired to dry as quickly as possible so as to prevent the recording paper from incidental staining with undried ink, and the coloring matter of ink fixed on the paper is desired not to fade out as long as possible.
In particular, the ink-jet recording system should satisfy the following requirements:
(1) Ink is quickly absorbed into recording paper. PA1 (2) An ink dot, when overlapping a previously applied ink dot, does not become disordered or diffused particularly in multicolor or full-color recording. PA1 (3) Ink dots do not diffuse on recording paper so as not to be enlarged more than needed. PA1 (4) The shapes of ink dots are close to a right circle and the perimeters of ink dots have smooth lines. PA1 (5) Ink dots have high optical density and distinct perimeter lines. PA1 (6) Recording paper exhibits a high whiteness and a good contrast to ink dots. PA1 (7) The color of ink does not vary depending upon recording paper used. PA1 (8) Ink droplets scarcely scatter around the dots they form. PA1 (9) Recording paper exhibits a minimum variation in dimensions due to elongation or wrinkles after recording.
While it has been known that satisfying these requirements is largely due to characteristics of the recording paper, in practice there has not been a plain paper or a specially finished paper, until now, that meets the above requirements. For example, the specially finished paper for ink-jet recording disclosed in Japanese Patent Kokai No. 74340/1977, though exhibiting a rapid absorption of ink, is liable to enlarge the diameters of ink dots and to make dim the perimeters of ink dots and exhibits a significant change in dimensions after recording.